Industrial Ultrasonic Technology

How It Works, Where We Apply It

Ultrasound: How It Works

Ultrasonic welding consists of a fusion process of ultrasonic frequency mechanical vibration between the sonotrode/horn and the localized surface to be welded.

The 50/60Hz frequency network is converted and amplified by the ultrasonic generator turning the electrical signal into energy through the transducer/converter.

This energy applied to the acoustical group must be supplied in sufficient quantity to overcome the inertial mass movements and friction between the parts to be welded.

The advantages of ultrasonic welding technology are numerous:

  • Brief welding cycles (from a tenth of a second to a second)
  • Absolute constancy
  • Ultra low energy consumption and only at welding phase
  • No filler material
  • Perfect esthetical results of the welded part, very resistant weld joint and ready to be used

Industrial applications of ultrasound

The ultrasonic technology is one of the safest, more efficient and faster method to join thermoplastic material.
The welding timing is around milliseconds and it is possible to weld printed materials and thermoplastic fabrics.

The ultrasonic technology allows to cut and in the same time close the synthetic fibres of fabrics, avoiding fraying of the materials. During and after the cutting operation the tool is always clean. Moreover operating with ultrasound is safe for operators: it does not burn and does not produce toxic fumes.

Thanks to the ultrasonic sewing technology is possible to join two or more layers of fabrics, without add any adhesives, solvents or mechanical fasteners. Moreover the ultrasonic sewing allows to obtain hermetical welding that preserve the content of the product. One of the advantage is for sure related on the energy; in fact the welding process has no negative impact.

The ultrasonic riveting allows to melt a pin, introduced in a special hole. The plastic pin is put in contact with the sonotrode by melting and forming a riveting head. This technique also allows to fix different materials or metal parts, such as elements for cars, campers and boats, or particular electrical components (plugs, sockets, connectors), or even air filters and gasoline/diesel filters.

This operation stems from the need to incorporate brass rivets in a thermoplastic material. Thanks to ultrasonic technology the hole in the plastic material melts, allowing the insertion of the rivet, that has a knurl that increase the welding grip. Once the welded plastic hardens, the rivet turns out perfectly incorporated.

Energy Directors in Ultrasonic Welding

To reduce the friction areas that don’t allow easily the welding process, it is recommended to create on the plastic materials small geometric protuberances called energy directors. To select and choose the best geometry of the energy directors It is possible to see here under some examples; in any case Sonomax is at disposal to offer the experience and the technical knowledge.

Here are some examples to choose the best geometry.

As shown by the pictures above, a triangular section on the joint serves to concentrate the energy of the ultrasound to allow the dissolution of the junction surface quickly.

Common joints that incorporate the use of an energy director, include: head-to-head, segment and male and female joints.

The above joints are recommended for hermetically sealed parts or for plastics that change rapidly from solid to molten state.
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